Hca3-O Fanouts: Z13S Versus Z114 / Zbc12 Servers - IBM z13s Technical Manual

In this case, a z13s-N20 is needed to fulfill all IFB connectivity, as shown in Figure 4-10.
Figure 4-10 HCA3-O Fanouts: z13s versus z114 / zBC12 servers
It is beyond the scope of this book to describe all possible migration scenarios. Always involve
subject matter experts (SMEs) to help you to develop your migration strategy.
The following list of considerations can help you assess possible migration scenarios. The
objective of this list is to enable migration to z13s servers, supporting legacy coupling where
essential, and adopting ICA SR where possible, to avoid the need for more CPC drawers and
other possible migration issues.
The IBM zEnterprise EC12 and BC12 are the last generation of z Systems to support
ISC-3, 12x HCA2-O, and 1x HCA2-O LR. They also are the last z Systems that can be
part of a Mixed CTN.
Consider Long Distance Coupling requirements first:
– HCA3-O 1x is the only long-distance coupling link that is available on z13s servers.
Keep slots free for HCA3-O 1x (LR) where possible.
– ICA SR or HCA3-O 12x should be used for short distance coupling requirements.
ISC-3 Migration (z13s servers do not support ISC-3):
– Evaluate current ISC-3 usage (long-, short-distance, coupling data, or timing only) to
determine how to fulfill ISC-3 requirements with the links that are available on z13s
servers.
– Your options are to migrate from ISC-3 to ICA SR, InfiniBand 12x, or 1x on z13s
servers.
– 1:1 Mapping of ISC-3 to Coupling over InfiniBand. On previous servers, the HCA2-C
fanouts enable ISC-3 coupling in the I/O Drawer. Two HCA2-C fanouts can be replaced
by two 1x fanouts (eight 1x links) or two 12x fanouts (four 12x links).
– ISC-3 supports one CHPID/link. Consolidate ISC-3 CHPIDs into ICA SR or IFB, and
use multiple CHPIDs per link.
180
IBM z13s Technical Guide